Traffic Engineering (TE) route computation in a single-region or a multi-region environment is the Central Processing Unit (CPU) intensive computation. Especially in the case of implementing a Constraint Shortest Path First (CSPF) algorithm, how to compute an optimal route is a complicated problem. In addition, in a network, a distributed computed node is hard to have a total Traffic Engineer Data Base (TEDB) in some cases. Therefore, a centralized special PCE is proposed in order to separate a path computation function from an Ingress node (physically or logically) in distributed computing.
In an existing Multi-region Network (MRN), a path is computed by using a separate TE PCE server to be responsible for related TE path computation functions. A unit that requests path computation is referred to as a Path Computation Client (PCC).
A PCE is a functional entity responsible for path computation in a network, and computes a TE path meeting constraint conditions, based on a known topological structure and constraint conditions of a network, according to the request of the PCC. The PCE may locate in any place of a network, and may be integrated in a network device, or may be a separate device. The Path Computation Client (PCC) requests the PCE to compute a path, and receives the path returned from the PCE. The PCC and the PCE, as well as the PCE and another PCE, communicate through a PCE Protocol (PCEP), and a PCEP message is used to submit a path computation request and obtain a path computation result.
In the path computation request in the current PCEP, only one filed “BANDWIDTH” is used to represent bandwidth traffic information of a path. FIG. 1 shows a specific format of the field “BANDWIDTH”, and the field is floating-point values. In an existing path computation method, the PCE computes a path according to the field “BANDWIDTH”. However, as the network is flattened and a variety of network technologies are converged, a node needs to support many switching capabilities, for example, wavelength switching, Time Division Multiplexing (TDM) switching, and packet switching. A network formed of such a node is an MRN, and Label Switch Paths (LSPs) of various Switching Granularity types coexist in the network, for example, a wavelength LSP, a TDM LSP, and an Ethernet packet switching LSP. Therefore, the existing path computation method cannot completely meet the path computation requirements in an MRN.